The above topic heading was a portion of somebody's post... original thread titled "To Use VPN Or Not" can be found here. I was going to reply to their post with this... There was a chance of thread hijacking, so I am starting a new one... If we are really picky, the only realistic killswitch is to turn off the router. Could those last handful of milliseconds before VPNetMon kicks in turn us into the lead actors/actresses in The Net 3.0? What about software to control other software... micro-delays are worth mentioning (compatability, system bottleneck, tweaking vs stock standard vs optimised)?
Well, firewall and routing rules are rather like "kill Switches", but they're arguably faster than custom apps. In Linux and *BSD, they work at the kernel level, as part of packet routing. And it's not like they're "turning off" anything. They're always deciding the fate of each packet, based on the established rules.
